1. Technical Field
Example embodiments of the present invention relate to a pulsed laser device, and more specifically to a high power ultra-short pulsed laser device which increases pulsed energy by using a resonator.
2. Related Art
After a laser was invented in 1960s, studies on application of the laser to industrial domain started from 1970s. From 1980s, the laser (especially, CO2 laser) has been applied to various application domains such as an industrial field, a medical field, a communication field, a display field, etc.
Also, a solid state laser appeared in 1980 due to development of a diode laser. Since the solid state laser can be applied to domains which a conventional gas laser cannot be used easily for, and demand for the laser has been increased. Accordingly, the laser is being applied to wide-range domains including an industrial domain such as a laser work, a laser cutting, a laser welding, a laser punching, a trimming, an etching, etc., a medical domain such as a dental treatment, removal of skin spot and tattoo, removal of hair, LASIK operation, etc., a study on interaction between laser and materials, a national defense technology domain, and a culture domain.
As industrial technology advances, high degree of precision and high productivity of the laser has been required. In order to meet the requirements, recently, femtosecond laser is being utilized widely for various domains.
The femtosecond laser has a property that light energy is converged during a very short time (10−15 of a second), and light is emitted. Accordingly, the femtosecond laser has different characteristics from conventional lasers. For example, since the femtosecond laser is illuminated on a medium during a time shorter than a time required for transferring heat to the medium when the laser is illuminated on the medium, an effect of heat or a thermal strain generated due to conventional laser operations may be prevented.
Also, since it is possible that the femtosecond laser fabricates a medium without damaging a surface of the medium, the femtosecond laser has been used for domains (such as semiconductors, electronic chips, medicine, etc.) requiring precise and fine processes.
However, in order to achieve an increased yield rate, a wider fabrication surface, etc., the femtosecond laser has a limit of output power for industrial purpose when it is used unilaterally. Therefore, it can be a restriction for enlarging its application domains.